Model study of adsorbed metallic quantum dots: Na on Cu(111)

We model electronic properties of the second monolayer Na adatom islands (quantum dots) on the Cu(111) surface covered homogeneously by the first Na monolayer. An axially-symmetric three-dimensional jellium model, taking into account the effects due to the first Na monolayer and the Cu substrate, has been developed. The electronic structure is solved within the local-density approximation of the density-functional theory using a real-space multigrid method. The model enables the study of systems consisting of thousands of Na-atoms. The results for the local density of states are compared with differential conductance ($dI/dV$) spectra and constant current topographs from Scanning Tunneling Microscopy.Comment: 10 pages, 8 figures. For better quality figures, download http://www.fyslab.hut.fi/~tto/cylart1.pd

Direct measurement of S-branch N(2)-H(2) Raman linewidths using time-resolved pure rotational coherent anti-Stokes Raman spectroscopy.

S-branch N(2)-H(2) Raman linewidths have been measured in the temperature region 294-1466 K using time-resolved dual-broadband picosecond pure rotational coherent anti-Stokes Raman spectroscopy (RCARS). Data are extracted by mapping the dephasing rates of the CARS signal temporal decay. The J-dependent coherence decays are detected in the time domain by following the individual spectral lines as a function of probe delay. The linewidth data set was employed in spectral fits of N(2) RCARS spectra recorded in binary mixtures of N(2) and H(2) at calibrated temperature conditions up to 661 K using a standard nanosecond RCARS setup. In this region, the set shows a deviation of less than 2% in comparison with thermocouples. The results provide useful knowledge for the applicability of N(2) CARS thermometry on the fuel-side of H(2) diffusion flames

Magnetic properties of Quantum Corrals from first principles calculations

We present calculations for electronic and magnetic properties of surface states confined by a circular quantum corral built of magnetic adatoms (Fe) on a Cu(111) surface. We show the oscillations of charge and magnetization densities within the corral and the possibility of the appearance of spin--polarized states. In order to classify the peaks in the calculated density of states with orbital quantum numbers we analyzed the problem in terms of a simple quantum mechanical circular well model. This model is also used to estimate the behaviour of the magnetization and energy with respect to the radius of the circular corral. The calculations are performed fully relativistically using the embedding technique within the Korringa-Kohn-Rostoker method.Comment: 14 pages, 9 figures, submitted to J. Phys. Cond. Matt. special issue on 'Theory and Simulation of Nanostructures

Interaction of Electromagnetic S-Wave with a Metal Film Located Between Two Dielectric Mediums

Generalization of the theory of interaction of electromagnetic S-wave with a metal film on a case of the film concluded between two dielectric environments is developed.Comment: 13 pages, 10 figure

Electromagnetic field correlations near a surface with a nonlocal optical response

The coherence length of the thermal electromagnetic field near a planar surface has a minimum value related to the nonlocal dielectric response of the material. We perform two model calculations of the electric energy density and the field's degree of spatial coherence. Above a polar crystal, the lattice constant gives the minimum coherence length. It also gives the upper limit to the near field energy density, cutting off its $1/z^3$ divergence. Near an electron plasma described by the semiclassical Lindhard dielectric function, the corresponding length scale is fixed by plasma screening to the Thomas-Fermi length. The electron mean free path, however, sets a larger scale where significant deviations from the local description are visible.Comment: 15 pages, 7 figure files (.eps), \documentclass[global]{svjour}, accepted in special issue "Optics on the Nanoscale" (Applied Physics B, eds. V. Shalaev and F. Tr\"ager

Role of bulk and surface phonons in the decay of metal surface states

We present a comprehensive theoretical investigation of the electron-phonon contribution to the lifetime broadening of the surface states on Cu(111) and Ag(111), in comparison with high-resolution photoemission results. The calculations, including electron and phonon states of the bulk and the surface, resolve the relative importance of the Rayleigh mode, being dominant for the lifetime at small hole binding energies. Including the electron-electron interaction, the theoretical results are in excellent agreement with the measured binding energy and temperature dependent lifetime broadening.Comment: 4 pages, 3 figure

A Novel Adaptation of a Parent-Child Observational Assessment Tool for Appraisals and Coping in Children Exposed to Acute Trauma

Background: Millions of children worldwide are exposed to acute potentially traumatic events (PTEs) annually. Many children and their families experience significant emotional distress and/or functional impairment following PTEs. While current research has begun to highlight a role for early appraisals and coping in promoting or preventing full recovery from PTEs, the exact nature of the relationships among appraisals, coping, and traumatic stress reactions as well as how appraisals and coping behaviors are influenced by the child\u27s environment (e.g., parents) remains unclear; assessment tools that reach beyond self-report are needed to improve this understanding. Objective: The objective of the current study is to describe the newly created Trauma Ambiguous Situations Tool (TAST; i.e., an observational child–parent interview and discussion task that allows assessment of appraisals, coping, and parent–child processes) and to report on initial feasibility and validation of TAST implemented with child–parent dyads in which children were exposed to a PTE. Method: As part of a larger study on the role of biopsychosocial factors in posttraumatic stress reactions, children (aged 8–13) and parents (n=25 child–parent dyads) completed the TAST during the child\u27s hospitalization for injury. Results: Children and parents engaged well with the TAST. The time to administer the TAST was feasible, even in a peri-trauma context. The TAST solicited a wide array of appraisals (threat and neutral) and coping solutions (proactive and avoidant). Forced-choice and open-ended appraisal assessments provided unique information. The parent–child discussion portion of the TAST allowed for direct observation of parent–child processes and demonstrated parental influence on children\u27s appraisals and coping solutions. Conclusions: The TAST is a promising new research tool, which may help to explicate how parents influence their child\u27s developing appraisals and coping solutions following a PTE. More research should examine the relationships of appraisals, coping, and parent–child processes assessed by the TAST with traumatic stress outcomes

Intensidades da poda seca e do desbaste de cacho na composição da uva Cabernet Sauvignon.

A pesquisa foi realizada durante quatro anos, num vinhedo de Cabernet Sauvignon (Vitis vinifera L.), em Bento Gonçalves-RS. O objetivo foi determinar o efeito das intensidades da poda seca e do desbaste de cacho em variáveis relacionadas aos componentes de produção da videira e à composição do mosto de uva. Os tratamentos consistiram em dois níveis de poda seca - curta e longa - e quatro de desbaste de cacho (%) - 0; 25; 50 e 75 -; com cinco repetições. O delineamento experimental foi o em blocos casualizados, com os tratamentos em parcelas subdivididas. Os resultados mostram que a poda seca e o desbaste de cacho tiveram efeito altamente significativo na produtividade do vinhedo que, na média dos quatro anos, variou de 10.971 kg/ha ? poda curta, 75% de desbaste ? a 32.819 kg/ha ? poda longa, 0% de desbaste. Houve, também, efeito significativo na produtividade por gema, peso de ramos podados por gema e por hectare, área foliar/peso fresco do fruto e produtividade/peso de ramos podados. Entretanto, o efeito nas variáveis relacionadas a açúcar e acidez do mosto da uva foi pouco expressivo. O componente 1 da análise de componentes principais discriminou o tratamento poda curta a 75% de desbaste de cacho dos tratamentos poda longa-0% de desbaste e poda longa-25% de desbaste